Bladud or Blaiddyd is a legendary king of the Britons, although there is no historical evidence for his existence. He is first mentioned in Geoffrey of Monmouth's Historia Regum Britanniae, which describes him as the son of King Rud Hud Hudibras, and the tenth ruler in line from the first king, Brutus, saying Bladud was contemporaneous with the biblical prophet Elijah.
A Bleydiud son of Caratauc is mentioned in the Welsh Harleian MS 3859 genealogies, suggesting to some that Geoffrey misinterpreted a scrap of Welsh genealogy. The Welsh form of the name is given as Blaiddyd in manuscripts of the Brut Tysilio. The meaning of the name is "Wolf-lord". In the text he is said to have founded the city of Bath. He was succeeded by his son Leir.
The tale of Bladud was later embellished by other authors, such as John Hardyng and John Higgins, writing in the fifteenth and sixteenth centuries.